1. Field of Invention
The present invention relates to a telecommunication system comprising a first station with a first transceiver, and at least a second station with a second transceiver, the first and second station being arranged for radio communication with each other. At least one transceiver comprises a receiver branch with a first phase-lock-loop for providing a first local oscillator signal, and a transmitter branch with a second phase-lock-loop for providing a second local oscillator signal, the first and the second phase-lock-loop respectively comprising a first and a second synthesizer, which are galvanically coupled with each other. Such a system can be a cordless telephone system, a cellular telephone system, or any system in which transceivers communicate with each other by radio.
The invention further relates to a station for use in such a system and to a transceiver for use in such a station.
2. Description of the Related Art
A system of this kind is well-known as a cordless telephone system, such as a system according to the CT1 or CT1.sup.+ Standard. The use of galvanically coupled synthesizers in a transceiver is known from a Philips Semiconductors Application Note for an Integrated Circuit of type UMA1015M, "Low-power dual frequency synthesizer for radio communications", June 1993, version 2.1 for Cordless telephone or Hand-held mobile radio, or the like.
A problem in a transceiver employing such an IC is interference of the transmitter branch with the receiver branch, i.e. a transmitter signal may be present in the spectrum of the local oscillator signal in the receiver branch. Such a problem is the more severe when the transmit and receive frequency are relatively close to each other, such as in the CT1 system or CT1.sup.+ system. In the German FTZ Regulation FTZ 1-TR2, or in the Dutch CEPT T/R 24-03 Regulation, regulations with regard to such so-called receiver spurious responses are given.